The goal of the proposed research is to supply fundamental information on the sensorimotor relationships that underlie the orientation functions of the mammalian superior colliculus. Specifically, this project will deal with a) the organization and processing of visual, somatic, and auditory inputs to the deep layers of the colliculus, b) the origins of deep layer projections that control head and pinna movements, and c) correlations between the organizations of sensory input and motor output. The proposed studies are largely anatomical, but also include physiological and behavioral experiments. Completion of this project should not only provide a clearer understanding of how the superior colliculus carries out its important role in orientation activites, but also yield new insight in the basic mechanisms of reflex function in the nervous system.